What is the difference between a mechanical wave and an electric magnetic way

What is the mass of sodium in 3 moles of sodium chloride

Calculate the number of kilojoules to warm 125 g of iron from 23.5°c to 78.0°c.

Astudent is trying to create a table that compares hypotheses, theories, and laws. hypothesis theory law do scientific researchers formulate it? yes yes yes does it explain why things happen? yes yes no yes yes yes is it used to make predictions? no yes yes which of the following questions would most likely fill the blank in the table? is it an intelligent guess? is it newly formulated? is it based on observations? has it been proved?